How to Diagnose American Foulbrood

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Every Time I’ve ever heard anything about American Foulbrood I’ve always heard that the disease comes with an odor. And while this is correct, often, by the time you can detect an odor, the disease has advanced.

There are other ways of telling if you might have American Foulbrood in your hive.

Symptoms and What to look for

-dark brood capping

-dead pupa

-sunken cells with a greasy or glossy sheen

-chewed cell perimeters

-scaley wax formation (especially visible when the frames are held at an angle)

-scale on cells

-an odor

The Rope Test

One way you can check to see if your hive might have American Foulbrood is to perform the rope test. This is a basic test that will indicate if you need to take further steps in diagnosing.

To perform the rope test, you insert a small object like the back end of a match tip into one of the cells. If the contents pulls up in a kind of sticky/slimy rope then you may have American Foulbrood.

Using a Test Kit

You can also order an American Foulbrood test kit, which is similar to a pregnancy type test. The most popular one is the Vita Diagnostics Test Kit

These tests are easy to use, fast and accurate. They are also a relatively inexpensive investment (about $14) considering what might be at loss if several of your hives become infected and must be destroyed. After researching for this article, we may incorporate it into our regular hive inspections as a preventative check up.

The tests come with complete instructions, and everything you need, but for the most part you will:

-Remove a larvae showing suspicious symptoms using the provided spatula

-Place the larvae in the extraction bottle and shake for 20 seconds

-Then using the pipet, suction up some of the liquid and drop 2-3 drops on the test strip (like a pregnancy test)

-If you get a control line only, no antibodies are found.

-If you get a second line, the hive is positive for American Foulbrood

If you get a negative result, but still suspect Foulbrood, you can also order a test kit for European Foulbrood, which is almost the same disease symptom-wise but caused by the bacteria Melissococcus plutonius. European Foulbrood tends to be less severe and less devastating than AFB.

American Foulbrood is caused by Paenibacillus larvae

If both these tests are negative then chalkbrood, sacbrood, other viruses might be at play. Varroa mites can also cause Parasitic Mite Syndrome.

Report any positive results to your veterinarian, state apiculturist or local county extension. They can help you manage the disease and keep it from spreading to other hives both in your own yard and your neighbors. Bees can fly great distances so if your hive is positive, you run the risk of infecting other beekeepers miles from your yard.

In my next post I will discuss treatment options, vaccines, natural cures and what to do if you have an American Foulbrood positive hive.